Atomic-Scale Mapping of an Emergent Interfacial Two-Dimensional Electron Gas at Anatase/LaAlO3

Abstract Atomic-level insight into structure, charge distribution, chemistry, and electronic states is essential for understanding emergent properties at oxide interfaces. Here, we leverage the quasi-strain-free anatase TiO2/LaAlO3 interface as an ideal model system to decouple intrinsic polar discontinuities from complex strain artifacts. By combining atomic-resolution electron energy loss spectroscopy with integrated differential phase contrast, we spatially map the electronic states associated with the formation of a two-dimensional electron gas (2DEG). This correlative approach enables the direct real-space disentanglement of intrinsic 2DEG-related states from extrinsic Ti3+ defect states. Supported by density functional theory and inelastic scattering simulations, we reveal a physical superposition: the intrinsic polar electronic reconstruction anchors metallic states directly at the boundary, while oxygen vacancies accumulate further into the film, acting as a donor reservoir. This work not only resolves long-standing ambiguities regarding oxide interfacial conductivity but also provides a robust, transferable framework for related material systems.